Reliable in-vivo measurement of phosphocreatine using 1H MRS offers valuable information for understanding brain energy metabolism. At 3T, separate quantification of phosphocreatine and creatine has been challenging using LCModel. This problem exacerbates in studies of deep hypothermic circulatory arrest (DHCA), a technique used in many cardiac surgeries, due to temperature-dependent chemical shifts. Furthermore, total creatine quantification is hampered using a 37°C-only basis set as it fails to account for the increased polarization at lower temperatures. By using a semi-laser sequence with temperature dependent LCModel basis sets, reliable quantification of phosphocreatine and total creatine was achieved for the DHCA studies.